Add Event::encode_data_to

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add `#[ink::contract_ref]` attribute - [#2648](https://github.com/use-ink/ink/pull/2648)
 - Add `ink_revive_types` (and remove `pallet-revive` dependency from `ink_e2e`) - [#2657](https://github.com/use-ink/ink/pull/2657)
 - non-allocating Solidity ABI encoder - [#2655](https://github.com/use-ink/ink/pull/2655)
+- Add `Event::encode_data_to` - [#2677](https://github.com/use-ink/ink/pull/2677)
 
 ### Changed
 - Marks the `pallet-revive` host function `account_id` stable - [#2578](https://github.com/use-ink/ink/pull/2578)

crates/env/src/engine/on_chain/pallet_revive.rs

@@ -995,14 +995,7 @@ impl TypedEnvBackend for EnvInstance {
             .chunks_exact(32)
             .map(|c| c.try_into().unwrap())
             .collect::<ink_prelude::vec::Vec<[u8; 32]>>();
-        let enc_data = scope.take_encoded_with(|buffer| {
-            let encoded = event.encode_data();
-            let len = encoded.len();
-            // NOTE: panics if buffer isn't large enough.
-            // This behavior is similar to `ScopedBuffer::take_encoded`.
-            buffer[..len].copy_from_slice(&encoded);
-            len
-        });
+        let enc_data = scope.take_encoded_with(|buffer| event.encode_data_to(buffer));
 
         ext::deposit_event(&enc_topics[..], enc_data);
     }

crates/env/src/event.rs

@@ -252,6 +252,10 @@ pub trait Event<Abi = crate::DefaultAbi>: AbiEncodeWith<Abi> {
 
     /// ABI encode the dynamic data of this event.
     fn encode_data(&self) -> ink_prelude::vec::Vec<u8>;
+
+    /// ABI encode the dynamic data of this event into the given buffer, and returns the
+    /// number of bytes written.
+    fn encode_data_to(&self, buffer: &mut [u8]) -> usize;
 }
 
 mod private {

crates/ink/macro/src/event/mod.rs

@@ -204,10 +204,15 @@ fn event_derive_struct(s: synstructure::Structure) -> syn::Result<TokenStream2>
             }
         );
 
-        let encode_data = match abi {
-            Abi::Ink => quote! {
-                ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_with(self)
-            },
+        let (encode_data, encode_data_to) = match abi {
+            Abi::Ink => (
+                quote! {
+                    ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_with(self)
+                },
+                quote! {
+                    ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_to_slice(self, buffer)
+                }
+            ),
             Abi::Sol => {
                 // For Solidity ABI encoding, only un-indexed fields are encoded as data.
                 let data_field_tys = data_fields.iter().map(|field| {
@@ -217,15 +222,24 @@ fn event_derive_struct(s: synstructure::Structure) -> syn::Result<TokenStream2>
                 let data_field_values = data_fields.iter().map(|field| {
                     &field.binding
                 });
-                quote! {
-                    match self {
-                        #pat => {
-                            ::ink::sol::encode_sequence::<( #( #data_field_tys, )* )>(
-                                &( #( #data_field_values, )* ),
-                            )
+                let ty = quote! { ( #( #data_field_tys, )* ) };
+                let val = quote! { ( #( #data_field_values, )* ) };
+                (
+                    quote! {
+                        match self {
+                            #pat => {
+                                ::ink::sol::encode_sequence::<#ty>(&#val)
+                            }
+                        }
+                    },
+                    quote! {
+                        match self {
+                            #pat => {
+                                ::ink::sol::encode_sequence_to::<#ty>(&#val, buffer)
+                            }
                         }
                     }
-                }
+                )
             },
         };
 
@@ -248,6 +262,10 @@ fn event_derive_struct(s: synstructure::Structure) -> syn::Result<TokenStream2>
             fn encode_data(&self) -> ::ink::prelude::vec::Vec<::core::primitive::u8> {
                 #encode_data
             }
+
+            fn encode_data_to(&self, buffer: &mut [::core::primitive::u8]) -> ::core::primitive::usize {
+                #encode_data_to
+            }
         })
     }))
 }

crates/ink/macro/src/tests/event.rs

@@ -57,6 +57,10 @@ fn unit_struct_works() {
                     fn encode_data(&self) -> ::ink::prelude::vec::Vec<::core::primitive::u8> {
                         ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_with(self)
                     }
+
+                    fn encode_data_to(&self, buffer: &mut [::core::primitive::u8]) -> ::core::primitive::usize {
+                        ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_to_slice(self, buffer)
+                    }
                 }
             };
         }
@@ -98,6 +102,10 @@ fn unit_struct_anonymous_has_no_topics() {
                     fn encode_data(&self) -> ::ink::prelude::vec::Vec<::core::primitive::u8> {
                         ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_with(self)
                     }
+
+                    fn encode_data_to(&self, buffer: &mut [::core::primitive::u8]) -> ::core::primitive::usize {
+                        ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_to_slice(self, buffer)
+                    }
                 }
             };
         } no_build
@@ -143,6 +151,10 @@ fn struct_with_fields_no_topics() {
                     fn encode_data(&self) -> ::ink::prelude::vec::Vec<::core::primitive::u8> {
                         ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_with(self)
                     }
+
+                    fn encode_data_to(&self, buffer: &mut [::core::primitive::u8]) -> ::core::primitive::usize {
+                        ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_to_slice(self, buffer)
+                    }
                 }
             };
         }
@@ -192,6 +204,10 @@ fn struct_with_fields_and_some_topics() {
                     fn encode_data(&self) -> ::ink::prelude::vec::Vec<::core::primitive::u8> {
                         ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_with(self)
                     }
+
+                    fn encode_data_to(&self, buffer: &mut [::core::primitive::u8]) -> ::core::primitive::usize {
+                        ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_to_slice(self, buffer)
+                    }
                 }
             };
         } no_build
@@ -234,6 +250,10 @@ fn custom_signature_topic() {
                     fn encode_data(&self) -> ::ink::prelude::vec::Vec<::core::primitive::u8> {
                         ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_with(self)
                     }
+
+                    fn encode_data_to(&self, buffer: &mut [::core::primitive::u8]) -> ::core::primitive::usize {
+                        ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_to_slice(self, buffer)
+                    }
                 }
             };
         } no_build
@@ -276,6 +296,10 @@ fn name_override_works() {
                     fn encode_data(&self) -> ::ink::prelude::vec::Vec<::core::primitive::u8> {
                         ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_with(self)
                     }
+
+                    fn encode_data_to(&self, buffer: &mut [::core::primitive::u8]) -> ::core::primitive::usize {
+                        ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_to_slice(self, buffer)
+                    }
                 }
             };
         } no_build
@@ -319,6 +343,10 @@ fn custom_signature_topic_precedence() {
                     fn encode_data(&self) -> ::ink::prelude::vec::Vec<::core::primitive::u8> {
                         ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_with(self)
                     }
+
+                    fn encode_data_to(&self, buffer: &mut [::core::primitive::u8]) -> ::core::primitive::usize {
+                        ::ink::abi::AbiEncodeWith::<::ink::abi::Ink>::encode_to_slice(self, buffer)
+                    }
                 }
             };
         } no_build